Timers

Timers fire a callback repeatedly on a fixed interval. Use them for polling, animation updates, clocks, or progress tracking.

Creating a timer

Call cx.add_timer() with an interval, an optional total duration, and a callback:

use vizia::prelude::*;
use web_time::Duration;

let timer = cx.add_timer(
    Duration::from_millis(100),  // interval
    None,                        // no fixed duration; runs until stopped
    |cx, action| match action {
        TimerAction::Start => {}
        TimerAction::Tick(_delta) => {
            cx.emit(AppEvent::Tick);
        }
        TimerAction::Stop => {}
    },
);

add_timer returns a Timer handle used to start and stop the timer.

Starting and stopping

Start the timer from a button press or event handler:

cx.start_timer(timer);

Stop it explicitly when it is no longer needed:

cx.stop_timer(timer);

TimerAction

The callback receives one of three actions:

Fixed duration timer

Pass Some(Duration) as the second argument to run for a fixed time and stop automatically:

let timer = cx.add_timer(
    Duration::from_secs(1),
    Some(Duration::from_secs(10)),
    |cx, action| {
        if let TimerAction::Tick(_) = action {
            cx.emit(AppEvent::SecondElapsed);
        }
    },
);

Checking timer state

Use cx.timer_is_running(timer) to query whether a timer is active:

if !cx.timer_is_running(timer) {
    cx.start_timer(timer);
}

See also

• Timed Events — one-shot scheduled events fired at a future time.